Many of these demonstrators are hardline, mask-wearing Ukrainian nationalists who answer only to a shadowy network of commanders.

But the task of steering Ukraine past the clashing rocks of violent revolution and unbridled authoritarianism has fallen in large measure into Mr Yatsenyuk’s hands.

When he spoke to the Telegraph, he stressed that the protests against President Viktor Yanukovych must be peaceful. “That is the trump card in our hands. This is the very solid negotiating position we have,” he said.

However, Mr Yatsenyuk’s meeting with the president on Thursday failed to reach any agreement. The opposition want Mr Yanukovych to resign and call immediate elections. He has offered only to reshuffle his cabinet and amend the country’s draconian anti-protest laws when Parliament reassembles on Tuesday.

Mr Yatsenyuk believes there is only one way out of the crisis: parliament must vote to dismiss the government. But what will happen if it fails to oblige on Tuesday?

“Unpredictable cycles — just unpredictable,” he replied. “It’s not about personalities. This is about the fate of this country. This is about the future of the Ukrainian state. The government has the leverage and the government has to use this leverage to resolve the crisis, but not to instigate and trigger another one.”

Mr Yatsenyuk believes the government has a tried and tested tactic: to distract its opponents with one crisis after another, while all the time, Ukraine moves further away from the European Union and steadily into the embrace of Russia.

“What they have been doing constantly — that’s their regular job — is not to resolve a crisis, but facilitate another one,” he said.

Ukraine occupies a pivotal strategic position as the biggest country in eastern Europe with a population of 46 million. But Mr Yatsenyuk believes that Western governments can do little to settle the crisis.

“We’ve asked the outside world to make telephone calls and have private talks with the president and, as far as I know, a number of Western leaders talked to the president, trying to convince him that he has to make some concessions,” he said. “You can’t negotiate if you provide concessions on the side of the opposition — and you get nothing on the side of the government. That’s not negotiations.”

Behind the government’s unbending response to the challenge from the streets lies a foreign power, or so Mr Yatsenyuk believes. He thinks that “somebody” has a “Plan B” to stamp out democracy and divide Ukraine by breaking off the largely Russian east.

Asked who this “somebody” might be, Mr Yatsenyuk declined to reply “Russia”, while making it obvious that he believes the Kremlin is behind everything.

“Guess who,” he said. “You guess who. A number of countries in this world have their own vision of democracy and their own style of democracy and they want to enlarge this space and to have another Berlin Wall.”

Against this background, Mr Yatsenyuk believes that Ukrainians can count on nobody but themselves. “It’s all up to us,” he said. “It’s all up to the Ukrainian people. But we still have a chance to avert the drama.”

That chance appeared to become more forlorn after this interview. On Saturday morning, the 24-hour confrontation between riot police and protesters at the triple barricade on Grushevskogo Street escalated once more. Police deployed a water cannon to quench the flames from blazing tyres.

The men on the barricades responded by throwing stones and chanting “bandits”. They pounded bats and clubs against home-made shields, keeping up a rhythmic thud-thud-thud as the water cannon turned thick clouds of black smoke into white.

A hardline statement from Vitali Zakharchenko, the interior minister, helped to explain the escalation. He made a series of accusations, perhaps preparing the ground for the demonstrations to be crushed by force.

The minister accused the protesters of murdering a policeman on Friday night. Any further negotiations were pointless, he added. “Everything that has happened in the capital in the last few days shows that our attempts to settle the conflict in a peaceful way did not give any result,” said Mr Zakharchenko.

He added that three more policemen had been kidnapped, of which one was in hospital and two were being held captive in City Hall, which has been occupied by the demonstrators. Mr Zakharchenko also accused protesters of “stockpiling” guns inside public buildings under their control. “The whole world should not close its eyes to these events,” added the minister.

Meanwhile, a protester died in hospital on Saturday, bringing the number of confirmed dead to three since Wednesday - although the opposition say that six have been killed.

The biggest demonstrations have traditionally taken place in Independence Square on Sundays. If the government want to prevent this gathering from happening this week, it has the option of launching an overnight operation to break through the barricades and forcibly clear the protest camps.

However, Mr Yatsenyuk and two other opposition leaders met President Yanukovych for further talks on Saturday. Whether they make any more progress than the previous failed session on Thursday remains to be seen.

On Saturday night the president's office issued a statement saying Mr Yanukovych had offered Mr Yatsenyuk the post of prime minister. It was not clear if he would accept, or how genuine the offer was.

After his meeting with the president, Mr Yatsenyuk addressed tens of thousands of protesters in Independence Square shortly after 10pm. He made no explicit mention of the offer of the premiership and neither accepted nor rejected the idea, saying only: "We are not scared of responsibility for the future of Ukraine."

By offering Mr Yatsenyuk the post of prime minister, the president has confronted him with a dilemma: accept the job and risk being labelled a sell-out, or reject the proposal and risk being seen as intransigent.

Many demonstrators have, in any case, lost faith in mainstream opposition leaders like Mr Yatsenyuk.

“We’ve had two months of peaceful protest - two months of them beating up activists, two months of them intimidating us, and now they have killed people,” said Andrii Sokolov, the “commandant” of a group that occupied the regional administration building in the western town of Lviv on Thursday.

Mr Sokolov describes himself as a trade unionist and social democrat, resenting any suggestion that far-right extremists are capturing the protest movement.

Instead, he said the government’s decision to meet peaceful demonstrations with force had radicalised its opponents. “The people can only take so much,” he said. “You’ve got to understand Yanukovych’s mentality: he’s a *zek* [a prisoner]. He only understands force. There is no other way forward now.”

Downstairs, a young protester in a balaclava, who gave him name only as “M”, was guarding a wing of the building occupied by Pravy Sektor, a secretive right-wing paramilitary group.

An English-speaking graduate, M said that he had joined the shadowy organisation out of rage when Mr Yatsenyuk and two other opposition leaders tried to negotiate a settlement with the president last Thursday.

“All they are negotiating with Yanukovych is how much they will get for selling out the people,” he said.

Pravy Sektor, or Right Sector, emerged as an alliance of far right groups when the protests began in November.

They have since become strong enough to take the initiative away from the mainstream opposition. And their members say bluntly they are at war.

“We are young, we don’t have children or wives, and that means we are able to give our lives for the revolution,” said M. “I joined because my younger brother said he was going to go. And at that point, I had to say I would go instead.” He added: “Joining was like jumping out of a plane: there is nothing underneath you and you don’t know where you are going to land.

Psychologically it was a pretty difficult thing to do. I cried when I left.

So did my mother.”

The rise of Pravy Sektor shows how sentiment among the pro-European opposition has changed - and how far things could go if a compromise is not reached.

This group has never accepted the idea of peaceful protest — members openly say that Mr Yanukovych will only be evicted by violent revolution.

That was not always a popular view. When the group first gained notoriety after violent clashes with police in Kiev on December 1, most protesters dismissed them as provocateurs, possibly paid by the government.

“We were right, and they were wrong - and now they are beginning to realise it,” said one coordinator for the group, who gave his name only as Mstislav.

Pravy Sektor is extremely secretive. The leaders are anonymous and none will reveal how many men are at their command. The group probably originated among neo-Nazis and football hooligans.

Both Mstislav and M denied having anything to do with “fascists” - though Mstislav conceded that “it’s a big organisation, and there could be some people like that”.

What is clear is that they are highly organised. A steady supply of gas masks, food and army surplus camouflage reaches the volunteers on the barricades. Former soldiers offer training in unarmed combat training outside the tent that serves as Pravy Sektor’s small base in Independence Square in Kiev.

Volunteers described a command system with multiple leaders, who command the rag-tag army deployed at the main barricade on Grushevskogo street in Kiev.

The question on the minds of many people is what such a powerful group outside the control of mainstream politicians would do if the revolution succeeds and the government falls.